The present disclosure relates to switching regulators, and in particular, to systems and methods for 100% duty cycle in switching regulators.
Switching regulators are used in a wide variety of electronic applications. One common application of a switching regulator is to generate a power supply voltage that supplies a regulated voltage to one or more integrated circuits (ICs). One example switching regulator is a buck regulator. In a buck regulator, a power source provides input voltage and input current. The power source is coupled to one terminal of a switch, which is commonly a switching transistor (e.g., a PMOS transistor). Another terminal of the switch is coupled to a load through a filter. In a buck converter, the output voltage is less than the input voltage. This is typically achieved by opening and closing the switch at a duty cycle according to the following equation:Duty Cycle=Vout/Vin.Buck switching regulators typically have a maximum duty cycle limitation for the switch of less than 100%. This limitation is a result of requirements from the control circuitry to be reset every switching period, such as slope compensation in a current mode architecture. If the controller for a buck regulator cannot support operation up to 100% duty cycle, this directly impacts the minimum input voltage to support a regulated output by a factor of Vout/duty cycle.